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Oilseed rape diseases, climate change, spread
and food security
Bruce Fitt1,2, Neal Evans2, Peter Gladders3, David Hughes1,2, Yong-JuHuang1,2, Jon West2, Ralph Lange4, Prem Kharbanda4
1 University of Hertfordshire, Hatfield, UK2 Rothamsted Research, Harpenden, UK3 ADAS Boxworth, nr. Cambridge, UK4 Alberta Research Council, Canada
Email: b.fitt@herts.ac.uk
Crop diseases threaten food security
• Crop losses to diseases decrease global food production despite
crop protection (16%, Oerke, J. Agr. Sci., 2006; FAO, 2010)
Diseases,
pests,
weeds
etc.
Actual crop losses
(with crop protection)
Potential crop losses
(without crop protection)
% £bn % £bn
Rice 37 74 77 154
Wheat 28 31 50 56
Maize 31 18 40 23
Potato 40 21 75 40
• Population 6 billion people AND
1 billion with not enough to eat FAO, 2009
Challenge - If global crop losses are decreased by 1%, an extra 25M
people will have enough to eat, without extra use of resources
(land,water etc.) (CABI, annual report, 2009/10)
Impacts of climate change on agricultural productivity by 2080sCline WR (2007), Global warming & agriculture; impact estimates by country
Climate change threatens food security
Climate change - Increased CO2, increased temperature
Air temperature at Rothamsted, Harpenden, UK
Oilseed rape diseases, climate change, spread and food security
1. Climate change adaptation: How can we be prepared for future impacts of climate change on disease epidemics and food security?
2. Disease spread; how can it be minimised?
3. Climate change mitigation: Can crop disease control reduce greenhouse gas emissions now?
Climate change can affect crop diseases
Crop(resistance)
Pathogen(changing population)
Environment(changing climate)
Disease
severity
Climate change scenarios
IPCC Special Report on Emissions Scenarios
Baseline (1960-1990)2020LO2020HI2050LO2050HI
LARS-Weather Generator
Semenov Agric. For. Met. 2000
• Combined climate &crop models
• Yields greatest inScotland
1980s 2050s High CO2
Butterworth et al., 2010, J. Roy. Soc Interface 7, 123-130
Climate change predicted to increase yields of
winter oilseed rape (if disease controlled),
especially in Scotland
Phoma stem canker of oilseed rape
UK losses £180 M; most severe in South
Weather-based forecast of risk of severe stem canker epidemics
Growth along leaf
petiole to produce
stem base canker
in spring
Increase in severity of
phoma stem canker
until harvest (summer)
Ascospore maturation and release;
infection of leaves in autumn
Summer Autumn
Spring Winter
Forecast date
1st leaf spotting
Forecast date
1st canker
Forecast canker severity
Evans et al., 2008, J. Roy. Soc Int. 5, 525-31
13-16 Sep
23-25 Sep
28-30 Sep
01-03 Oct
04-06 Oct
07-10 Oct
11-13 Oct
14-16 Oct
17-19 Oct
20-23 Oct
27 Oct
Forecast dates (10% plants with phoma leaf spot)
2010/2011 winter oilseed rape growing season
http://www.rothamsted.ac.uk/leafspot/
Stonard et al., 2010, Eur. J. Plant Path. 126, 97-109
• Combined climate &
yield loss models
• Yields
(susceptible cultivars)
in England will halve
Hi1980sgh2050s High
Climate change predicted to halve yields in
England without disease control, due to
increasing severity of phoma stem canker
CO2
Butterworth et al., 2010, J. Roy. Soc Interface 7, 123-130
Autumn
Summer Spring
Winter
Air-borne ascospores Phoma leaf spots
Infection
Damage
R gene resistance
Quantitativeresistance
Quantitativeresistance
Early phoma canker
Severe canker (harvest)
Time of RL resistance rating
Climate change & Brassica resistance to L. maculans
Fitt et al., 2006, Eur. J. Plant Path. 114, 3-15
Major gene Rlm6 mediated resistance to
L. maculans is temperature-sensitive
Cultivar
DarmorDarmorMX (Rlm6)
25°C
15°C
Near-isogenic-lines (INRA Rennes)
16 days
post inoculation
Huang et al., 2006, New Phytologist 170, 129-141
Resistant
Susceptible
DarmorMX (Rlm6)
15°C
36 days
after leaf
inoculation
Darmor
25°C
30 days
after leaf
inoculation
Effects of temperature on Rlm6 resistance to L. maculans
(leaves inoculated with conidia of GFP AvrLm6)
L.maculans
labelled with
Green Fluorescent
Protein(Eckert et al., 2005, FEMS
Microbiol. Lett. 253, 67-74)
Temperature effects on quantitative resistance(CE experiments)
Darmor (with quantitative resistance)
Eurol (without quantitative resistance)
Huang et al., 2009, Plant Pathology, 58, 314-323
0
20
40
60
80
100
15 °C 25 °C
Ste
m c
an
ker
severi
ty
(% a
rea a
ffecte
d)
Darmor
Eurol
Disease control - crop resistance, e.g. against Leptosphaeria
maculans (phoma stem canker of oilseed rape)
Resistant crop Susceptible crop
R gene no longer effective
(pathogen had changed)
90% yield loss
Most severe stem canker epidemics in Australia (Mediterranean climate, photos Steve Marcroft)
Canker - global crop losses >£1200 M annually, despite crop protection
Leptosphaeria maculans genome paper published
• Rouxel et al. Nature Communications (Feb 2011)
• L. maculans ‘brassicae’ genome size 45.12 Mb
• 17-18 chromosomes
• Avr (effector) genes often in regions with many transposons
Improve understanding of major gene resistance to
L.maculans
Brassica napus –
Resistance (R) genes*:
Rlm1
Rlm4/Rlm7
Rlm6
L. maculans – Corresponding Avr genes:
Avrlm1+
Avrlm4/7+
Avrlm6+
x*12 Rlm resistance
genes reported to date+ recently clonedby INRA
Air sampling to determine pathogen races
0
20
40
60
80
AvrLm1 AvrLm6
All
ele
fre
qu
en
cy
(%
)
2006/07
2007/08
2008/09
b
Advantages; samples larger population, quicker, cheaper, less laborious than cotyledon assays
Van de Wouw et al., 2010
1. Adaptation; preparing for effects of climate
change on crop diseases - conclusions
• Predict increase in OSR yield if diseasecontrolled; need disease resistance thatoperates at higher temperatures
• Predictions can guide government/industryforward planning by identifying diseases that willbecome more important to ensure future foodsecurity
2. Spread; Phoma stem canker;
two co-existing pathogens & two diseases
L.maculans
L.biglobosa
Upper stem
lesion
Stem base canker
Data from A Dimaghani & B Howlett
L.b. brassicae
L.b. canadensis
L.b. occiaustralensis
L.b. australensis
Europe
Middle EastAsia
PacificIslands
Australia
SouthAmerica
CentralAmerica
NorthAmerica
Africa
Georgia
Chile
China
Canada
Worldwide distribution of L. biglobosa sub-species
Dilmaghani et al., 2009; Van der Wouw et al., 2008
A
B
A/B
1975-98
2001`
1994-2007
Lm
Lb
Lm +
Lb
L. maculans spreading into areas colonised by L. biglobosa
•Before 1975: only L. biglobosa in Canada
•1975: L. maculans in Saskatchewan
•1983: L. maculans in Alberta (Lloydminster)
•1984-1998: spread west across Alberta
Leptosphaeria maculans spread into Canada (Alberta)
Disease control strategies used in Alberta
• Survey to monitor spread of Leptosphaeriamaculans
• Regulatory: Alberta Pests Act 1984 required clean seed, allowed destruction of crop
• Cultural: mandatory crop rotation 1 crop in 4
• Technology transfer / education –
Training farmers/advisors to recognize, control phoma stem canker
• Intended to delay spread of Leptosphaeriamaculans until resistant cultivars became available
Short-term strategyDestruction of crops with L. maculans
Short-term strategyPhoma stem canker survey (Alberta)
• 1983-1998
• 950 crops per year
• 50 plants per crop
• Lab diagnostics
• 4500 data points for modelling
Modelling westward spread of L.maculans across Alberta
1989
Longitude
2 4 6 8 10 12 14 16 18 20 22 24 26 28
La
titu
de
2
4
6
8
10
12
14
16
18
20
22
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1992
Longitude
2 4 6 8 10 12 14 16 18 20 22 24 26 28
La
titu
de
2
4
6
8
10
12
14
16
18
20
22
0.0
0.2
0.4
0.6
0.8
1.0
1995
Longitude
2 4 6 8 10 12 14 16 18 20 22 24 26 28
La
titu
de
2
4
6
8
10
12
14
16
18
20
22
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1998
Longitude
2 4 6 8 10 12 14 16 18 20 22 24 26 28
La
titu
de
2
4
6
8
10
12
14
16
18
20
22
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
Latitu
de
Longitude
1989
19981995
1992
(including phoma stem canker disease nursery)
Long-term strategy: Breeding disease resistance
SusceptibleWestar
More resistant
1994
Resistant cultivars became available 1988 – 1995
2. Spread; conclusions
Canadian example can provide lessons for others
● Combination of short-term strategies to decrease spread of L. maculans with long-term strategies
● Short-term; survey, regulation, crop management
● Long-term; resistance breeding; fungicide development
• Agricultural GHG account for 7% of UK total emissions
• The UK target for agriculture in England is to cut GHG
by 3Mt CO2 by 2020.
“... a sustainable
and secure food
system for 2030 ...”
launched 2010
3. Mitigation – can crop disease control contribute?
Mahmuti et al. Int J Agr Sust 7, 189-202 (2009)
0 200 400 600 800 1000 1200 1400 1600
Kg CO2 eq. ha-1
Most GHG to produce 1 ha winter oilseed rape
associated with Nitrogen fertiliser
Fungicides
Herbicides
Insecticides
Lime
P2O5
K2O
N2O (soil)
N
Seed
Field Operations
(manufacture)
(emissions)
600
800
1000
1200
2005 2006 2007 2005 2006 2007
kg
CO
2 e
q.
t-1
untreated
treated
Rothamsted ADAS
Phoma canker
Light leaf spot
ADAS sites were Teversham (2005) and Boxworth (2006-2007)
Treatment with fungicide to control diseases decreases GHG emissions
per tonne seed winter oilseed rape
Fungicides to control disease increase yield & decrease GHG emissions
(in UK wheat, oilseed rape, and barley)
winter wheat winter OSR winter barley spring barley
• Disease control with fungicides or crop resistance decreases GHG emissions
• These GHG reductions contribute to UK targets
3. Mitigation; disease control to combat
climate change - conclusions
Hughes et al., Pest Management Science, 2011, pub-on-line
Crop diseases and climate change
1. Need information to guide strategies for
adaptation to impacts of climate change on crop
diseases losses
2. Need publicity to show how improved crop
disease control can contribute to climate change
mitigation
3. Need vigilance to maintain/improve crop disease
control despite changing pathogen/climate to
ensure global food security
ThanksPlant-pathogen-climate interactions group, Rothamsted
Other contributors to work
• Mike Butterworth
• Regine Delourme et al., INRA
• Maria Eckert
• Simon Edwards, HAUC
• Graham King
• Martin Mahmuti
• Steve Marcroft (Aus. photos)
• Eric Ober
• Thierry Rouxel et al., INRA
• Pierre Stratonovitch
• Sue Welham
Funding
• Modelling – BBSRC;
PASSWORD project; HGCA
and partners/Defra LINK
• Climate change – BBSRC
ISPG, CLIMDIS/OREGIN
projects;Defra
Andreas BaierlMikhail SemenovRodger White
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